| A | B |
|---|
| signal-transduction pathway | a mechanism linking a mechanical or chemical stimulus to a specific cellular response |
| local regulator | a chemical messenger that influences cells in the vicinity |
| hormones | chemical signals found in all multicellular organisms that are formed in specialized cells, travel in body fluids, and coordinate the various parts of the organism by interacting with target cells |
| reception | the target cells detection of a signal coming from outside the cell |
| transduction | a DNA-transfer process used by phages to carry bacterial genes from one host cell to another |
| response | may be almost any imaginable cellular activity that occurs at the right time, in the right cells and in proper cordination with the other cells of the organism |
| ligand | a molecule that binds specifically to a receptor site of another molecule |
| G-protein-linked receptor | a signal receptor protein in the plasma membrane that responds to the binding signal molecule by activating a G protein |
| G protein | attached to the cytoplasmic side of the membrane, it functions as an on or off switch |
| tyrosine kinase | an enzyme that catalyzes the transfer of phosphate groups from ATP to the amino acid tyrosine on a substrate protein |
| tyrosine-kinase receptors | a receptor protein in the plasma membrane that responds to the binding of a signal molecule by catalyzing the transfer of phosphate groups from ATP to tyrosines on the cytoplasmic side of the receptor |
| ligand-gated ion channels | protein pores in the plasma membrane that open or close in response to a chemical signal, allowing or blocking the flow of specific ions |
| protein kinase | an enzyme that transfers phosphate groups from ATP to a protein |
| protein phosphatases | an enzyme that removes phosphate groups from proteins, often functioning to reverse the effect of a protein kinase |
| second messengers | a small, nonprotein, water-soluble molecule or ion that relays a signal to a cells interior in response to a signal recieved by a signal receptor protein |
| cyclic AMP or cAMP | cyclic adenosine menophosphate, a ring-shaped molecule made from ATP that is a common intracellular signaling molecule in eukaryotic cells |
| adenylyl cyclase | an enzyme that converts ATP to cylic AMP in response to a chemical signal |
| diacylglycerol (DAG) | a second messenger produced by the cleavage of a certain kind of phospholipid in the plasma membrane |
| inositol trisphosphate | a second messenger that functions as an intermediate between certain nonsteroid hormones and a third messenger |
| calmodulin | an intraellular protein to which calcium binds in its function as a second messenger in hormone actions |
| scaffolding proteins | a type of large relay protein to which several other relay proteins are simultaneously attached to increase the efficiency of signal transduction |
